Trichothecene production and pathogenicity of Fusarium tumidum, a candidate bioherbicide for gorse and broom in New Zealand

The relationship between trichothecene production and pathogenicity was inv estigated for 29 isolates of Fusarium tumidum, a potential bioherbicide for gorse (Ulex europaeus) and broom (Cytisus scoparius) in New Zealand. All i solates originally derived from broom produced high levels of T-2 tetraol d erivatives when grown on ground maize kernels and pearl barley grains, comp ared with isolates from gorse. Low amounts of scirpentriol derivatives were also produced by both groups of isolates. No nivalenol and deoxynivalenol derivatives were detected in any of the culture extracts. A subset of isola tes cultured on gorse and broom tissue produced only small amounts of T-2 t etraol derivatives relative to the amounts produced in grain cultures. Over all, isolates from broom were more aggressive towards both hosts than isola tes from gorse, but the pathogenicity of isolates was not correlated with t heir capacity to produce large amounts of T-2 tetraol derivatives in cultur e. Two isolates from gorse were highly aggressive towards both weeds. These isolates offer prospects for the development of a safe bioherbicide that c ould target two major weeds in New Zealand, as trichothecenes were not dete cted from them at the higher concentrations.